The United States and the rest of the world are facing significant challenges in finding sustainable replacements for petroleum products, which are extensively used for agriculture and transportation. Cultivated or farmed phototropic organisms, such as algae, are excellent candidates for meeting both needs, as well providing a feedstock for a variety of other products, including nutraceuticals and plastics, to name but a few. It should be understood that while the concepts disclosed herein can be applied to many different types of phototropic organisms, such concepts are particularly well suited to the cultivation of algae, both naturally occurring and engineered strains. Development of a cost-effective algae cultivation system is a key to facilitating wide-scale adoption of algae biomass farming.
The worldwide demand for algae biomass is growing. In the near future the market for nutraceuticals derived from algae (as forecast by the Nutrition Business Journal) is expected to be $500 billion in the U.S. alone, and over $2 trillion worldwide, with room for substantial growth. Pike Research predicts that the biofuel market will grow to $247 billion by 2020, up from $76 billion in 2010. The Biofuels Digest projects that algal biofuel capacity will reach 1 billion gallons by 2014. Algae wholesalers are targeting an annual production of 1.62 billion gallons, at a wholesale cost of $1.30 per gallon in 2014.
Global demand for alternative fuels is expanding, due to population growth, increased attention to energy security, and environmental policy mandates. For example, the Environmental Protection Agency established a renewable fuel volume requirement of 1.35 billion gallons in 2011. The U.S. Navy has publically announced its goal of fueling at least 50 percent of its fleet using renewable fuel sources by 2020. Achieving that objective will require a significant use of biofuels. There is also a growing demand for bio sourced oils to supplant the market currently met using soy oil and rapeseed oil.
A study by the University of Minnesota indicates that algae derived biomass performs as well as alfalfa in dairy cattle diets. If cultivation techniques can be provided on a cost effective basis, cultivated algae can provide a valuable oil fraction, a high-value protein co-product, and algae derived meal for animal feed; all while absorbing carbon dioxide from greenhouse gas emissions.
The following algae facts provide insight as to the potential of algae cultivation:
Algae's growth is phenomenal: to translate it agriculturally, algae crops grow 20 to 30 times faster than any other food crop.
Output is staggering: algae can produce 6,000 gallons of oil and 98 tons of meal per acre—every year. That's about 30 to 100 times more than other alternative biofuel sources, such as soybeans.
Algae biomass provides the most rapidly harvestable biofuel feedstock: Algae colonies can reach harvest size in as little as 48 hours, and appropriately designed cultivators can harvest algae biomass continuously.
Algae biomass absorbs large amounts of carbon dioxide (CO2) while growing. Approximately 180 tons of CO2 are absorbed annually from the atmosphere per acre of algae, and algae absorbs other greenhouse gases as well.
Appropriately designed cultivators make very efficient use of water; 85-97% of all water can be recovered and reused.
Algae biomass derived oil is suitable for use in existing petrochemical refineries and distribution systems. Ethanol, in comparison, is an aggressive solvent; requiring modifications to existing infrastructure, resulting in additional cost.
Algae biomass derived meal is high in protein (39%) and is suitable for use as animal feed and as nutritional supplements. Algae are even used directly as a food source by consumers in some cultures.
Algae-based fuels are considered to be carbon neutral. When burned, they offer a 50 to 80 percent reduction in particulate emissions versus fossil fuels, with no loss of power. Carbon emissions from algae derived fuel is offset by the CO2 absorbed from the atmosphere during the cultivation of algae.Algae-based fuel is naturally sulfur-free (sulfur needs to be removed from some types of petroleum crude oil, increasing the cost of refining).Just 15,000 square miles of algae farms could replace all the petroleum used in the U.S. per year, according to the Department of Energy. That is about one-sixth the size of Minnesota.
There is a need for methods and apparatuses to efficiently cultivate phototropic organisms such as algae. There is a need for an algae growing system that a farmer can purchase, and within one or two months be growing algae, monitoring his crop for nutrients and harvesting using computerized controls. Such a system should have a return on investment (ROI) measured in a number of years, and that ROI should be competitive with the ROI on conventional farm equipment, such as tractors, cultivators, and other agricultural tools having a life cycle suitable for financing.
Some biofuel companies have emphasized algae growing systems that have high production rates, yet are capital and labor intensive. Others have emphasized open-pond systems that have low capital investment requirements, but are susceptible to environmental contamination and harsh weather extremes in most locations. There is a need for algae cultivating systems that operate with good yield, high reliability and low maintenance, but require a modest capital investment, thus providing a predictable financial return. There is also a need for energy efficient and economical growing systems that do not require large amounts of electrical or chemical energy for heating the biomass cultivations in the spring and fall seasons in temperate zones to keep them at optimal growing temperature during the early morning and late afternoon hours. Similarly there is a need for energy efficient and economical growing systems that do not require heat- or electricity-driven refrigeration systems in the summer to cool the biomass cultivation. Using electricity or natural gas for daily heating and/or cooling of the biomass cultivation may render the growing operation non-viable from an economic standpoint.
There is a need for all-weather, temperate-climate algae cultivating systems that are easily deployable, easy-to-use, easy-to-clean, and cost effective. In temperate climates, summer daytime temperatures can be too hot for growing certain algae, but summer nights generally cool off substantially. In the spring and fall, day time temperatures are good for growing, mornings are often quite cold, and often at or near freezing conditions. Because of these seasonal variabilities in high and low temperature extremes, and because of large diurnal temperature swings, there is a need for algae growing systems that are energy-efficient, such that they do not require large externally-supplied energy loads for heating and cooling the growth media to keep it at or near its optimal growing temperature.